Landfill and Environmental Remediation Liabilities - Changes (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Landfill and environmental remediation liabilities
Interest accretion	$ 26	$ 24
Ending balance, environmental remediation	218
Landfill [Member]
Landfill and environmental remediation liabilities
Beginning balance, landfill	2,156
Obligations incurred and capitalized	26
Obligations settled	(16)
Interest accretion	26
Revisions in estimates and interest rate assumptions	7
Ending balance, landfill	2,199
Environmental Remediation Liabilities [Member]
Landfill and environmental remediation liabilities
Beginning balance, environmental remediation	230
Obligations settled	(5)
Revisions in estimates and interest rate assumptions	(7)
Ending balance, environmental remediation	$ 218

Total costs accrued as of the balance sheet date for environmental loss contingencies.

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